When you bolt the toilet down, the floor is no longer floating. You've anchored the floor in that spot too. That said, the bathroom floor in my S&B house is vinyl plank with the toilet anchored over it and its fine. However, the vinyl in a house isn't subject to as much movement as in an RV, which gets vibration, flexing and a lot of temperature & humidity change.
Re your slide, does it have rollers or skids that touch the flooring? If so, I don't think a floating floor works. It is going to move a lot when the slide drags on it. I'd glue it down if that's the case. The better grades of vinyl plank usually have alternate instructions for using adhesive (non-floating), but you might have to find them on the flooring manufacturer's website rather than in the box.
Former owner of 2004 American Tradition and several other RVs
Home is West Palm Beach, FL